1. Field of the Invention
This invention relates generally to devices that convert solar and/or waste heat energy to electricity, the electricity in turn being used in an electrolysis process to make hydrogen gas from water, which hydrogen then in turn is used to make gaseous and liquid fuels via the reaction of hydrogen gas with CO2 gas when exposed to the presence of heat, temperature and/or catalytic materials. More specifically, it relates to devices that use metal hydride heat engine technology to convert the solar and/or waste heat energy into electrical energy which in turn is used to make Hydrogen gas via the electrolysis of water, which then in turn is used to make gaseous and liquid fuels via the reaction of the hydrogen gas with CO2 gas when exposed to the presence of catalytic materials and/or heat and temperature.
2. Background Art
Thermal hydrogen compressors for a broad range of applications have been known for over twenty years. Thermal compression of hydrogen using reversible metal hydride alloys offers an economical alternative to traditional mechanical hydrogen compressors. Hydride compressors are compact, silent, do not require dynamic seals or excessive maintenance and can operate unattended for long periods. When powered by “waste” heat, total energy consumption is only a fraction of that required for mechanical compression, which reduces the cost of hydrogen production and increases energy use efficiency. The simplicity and passive operation of the thermal compression process offer many advantages over mechanical compressors. Hydrogen compressors of this type are described in U.S. Pat. No. 4,282,931 and commonly owned U.S. Pat. Nos. 4,402,187; 4,505,120; 5,450,721; 4,781,246; 4,884,953; 5,623,987 and 6,508,866, the disclosures of which are all incorporated by reference herein, as appropriate.
The common thread in all of the heretofore known hydride compressor technologies is the use of metal hydrides to absorb and release hydrogen at predesignated appropriate times in the hydriding/de-hydriding cycle so as to compress the hydrogen to ever higher pressures. Hydrogen pressure in a metal hydride is known to increase exponentially with increasing temperature. The pressure rise generated in a single stage hydride heat exchanger may be as high as 300%. Although theoretical pressure increase is calculated to be as much as 500%, natural inefficiencies, such as heat transfer resistance and hydrogen pressure drop, tend to reduce the increase in actual practice.
The high pressure hydrogen gas generated by the hydride compressor can be expanded through a turbine/electric generator type of device to produce shaft power and electric power. Electric power plants are capable of converting the high-pressure steam or water pressure created in a generator at a dam into electricity. Other methods, for example, direct solar to electricity conversion in solar panel or battery power, can be used to generate an initial amount of electricity to run an electrolyzer for converting water into oxygen and more importantly hydrogen in an electrolysis process resulting in the production of and oxygen gas. The hydrogen is then used in further processing, as will be explained below in further detail.
When a repeating cycle of hydrogen absorption and desorption is used in a heat exchange cycle, as in, for example, aforementioned U.S. Pat. Nos. 5,450,721, and 5,623,987 and in U.S. Published Application No. 2005/0274138, hydrogen absorption in a metal hydride alloy as used in heat exchange units is known to be accompanied by a heat of formation which is exothermic. In order to continuously absorb hydrogen to an alloy's maximum capacity, heat must be removed from the bed at an appropriate stage in the cycle. The rate at which a hydride alloy can absorb or release hydrogen is dependent upon the rate at which heat can be transferred into or out of the alloy. Increasing the heat transfer rate will allow the processing of higher flow rates, or alternatively, the same flow rate can be processed by proportionately smaller amounts of alloy. Therefore, small containers capable of rapid heat transfer can handle high flow rates. Alternatively, containers having high surface to volume ratios, such as those described in aforementioned U.S. Pat. No. 5,623,987, may be utilized to simultaneously provide rapid heat and hydrogen transfer through the system.
More recently, photovoltaic technology has long been known to convert solar energy directly into electricity. In ongoing research, government agencies, laboratories and private companies endeavor to make this technology commercially viable and historically have met with limited success. These efforts are taking on new urgency and are expected to multiply in view of the world's appetite for energy and depletion of natural gas and petroleum resources. The search for such alternative energy production has also become critical in view of the need to reduce carbon emissions so as to protect the worldwide environment from climate change due to a general warming of the world's troposphere.
Using the electricity produced by solar photovoltaics in an electrolyzer to produce Hydrogen gas is also well known. However, a unitary system or process wherein hydrogen derived from electrolysis and then reacting it with carbon dioxide to make gaseous and liquid fuels has not yet been posited, despite recognized promise to remove carbon from the atmosphere and the production of fuels without utilizing carbon emission fuels from the ground.